The present invention relates to lens apparatuses mountable on image-pickup apparatuses such as video cameras and digital still cameras.
A lot of image-pickup systems are used, each including an image-pickup apparatus equipped with an image-pickup element such as a CCD sensor or a CMOS sensor and a lens apparatus interchangeably mounted on the image-pickup apparatus. Such a lens apparatus has been disclosed in, for example, Japanese Patent Laid-Open application No. H09(1997)-243899. The disclosed lens apparatus is provided with communication contacts on its mount portion for attaching the lens apparatus to an image-pickup apparatus. The communication contacts form communication paths between a lens side microcomputer and an image-pickup apparatus side microcomputer in the image-pickup system. Exposure information obtained in the image-pickup apparatus is sent to the lens apparatus through the communication paths, and then an iris driver provided in the lens apparatus is operated to perform auto exposure.
Recent image-pickup apparatuses use an image-pickup element capable of high-resolution image pickup, which has four to ten million pixels with a narrower pitch. In addition, image-pickup systems are used, which can record high-definition (HD) images with a much higher resolution than that of conventional television images not only in still image pickup but also in video image pickup.
Such image-pickup systems are often used by professional camera operators, and they generally prefer manual focusing to auto focusing.
In such a situation, correct determination of a manual focusing state through an electronic viewfinder provided on the image-pickup apparatus requires that images displayed on the electronic viewfinder have a resolution equivalent to images to be recorded. However, achieving this requires increasing the size of the electronic viewfinder, resulting in hindering reduction in size, weight and cost of the entire image-pickup apparatus.
As a method for enabling the correct determination of the manual focusing state through the electronic viewfinder, a function to display an enlarged image of the central part of the picked up image in response to operator's operation can be employed. Specifically, an operating switch is provided, which enables changing display mode setting between a normal display mode for displaying a normal-sized image to grasp the entire picked up image and a large display mode for displaying an enlarged image of part of the picked up image to confirm the focusing state.
However, manual focusing is performed in response to rotational operation of a focus ring provided on the lens apparatus. On the other hand, the operating switch to change the display mode between the normal display mode and the large mode is generally provided on the image-pickup apparatus equipped with the electronic viewfinder. In this case, the camera operator has to move his/her hand widely between the lens apparatus side and the image-pickup apparatus side when operating the focus ring and changing the display modes. This makes operation difficult, thereby hindering smooth image pickup.
Japanese Patent Laid-Open application No. H09(1997)-243899 has disclosed a technique to perform optical zooming in the lens apparatus and electronic zooming in the image-pickup apparatus seamlessly in response to operation of a zoom ring provided on the lens apparatus. Also in this image-pickup system, a switch to turn on and off the electronic zooming function is provided on the image-pickup apparatus. Therefore, the camera operator has to release his/her hand from the zoom ring and then move it widely to the image-pickup apparatus as in the above-described operation to change the display mode between the normal and large display modes. In other words, the operation becomes difficult, thereby hindering smooth image pickup.
Furthermore, there is a case where a lens apparatus is provided with a manual ring for operating an aperture stop, and an image-pickup apparatus is provided with an electronic shutter function (that is, a function to change the charge accumulation time of the image-pickup element) and a switch for setting this function. In this case, the operation becomes difficult since the operating members are separated from each other between the lens apparatus side and the image-pickup apparatus side, though both are provided for functions relating to the same exposure control.